[kbinkster]

Well, I cannot find the post I remembered. Maybe it is not on this forum, or maybe whatever problem there was has been resolved and the post was deleted.

But, there were problems with purity, which is why you aren't seeing the heat you had with two linked concentrators. I don't know what anyone plans to do, but there is a 6 month warranty in place. If your M20 isn't performing as it should, and your purchase was recent enough to be covered, you could see about having it repaired/replaced. I have read about So. Central Cryo./Unlimited Oxygen standing behind their products. I know that they are working with GTT on resolving the problem about the bad units they got. So, you should be taken care of, I would think.